import java.util.Scanner;
public class ball
{
	public static void main(String args[])
	{
		Scanner scanner=new Scanner(System.in);
		System.out.println("请输入半径：");
		double r=scanner.nextDouble();
		double v=Math.PI*r*r*r*3/4;
		System.out.printf("球的体积=%f",v);
	}
}